Carburetor throttle mechanism



Dec. 2, 1958 E. OLSON 2,862,487

CARBURETOR THROTTLE MECHANISM Filed Oct. 17, 1956 :s Sheets-Sheet 1 v INVEN TOR. 67/2267 0/5022 A T TORNE Y Dec. 2, 1958 E. OLS ON 2,862,487

CARBURETOR THROTTLE MECHANISM Filed Oct. 1'7, 1956 Sheets-Sheet 2 Imvuvrox.

I (a, 2 m v 1 fi/fij I rron/var Dec. 2, 1958 E. oLsoN CARBURETORTHROTTLE MECHANISM 3 Sheets-Sheet 5 Filed Oct. 17, 1956 INVENTOR. M67/2721 0/5022 ATTORNEY CARBURIETQR THRGTTLE MEfIl-IANISM ElmerOHson,;Roehester, N. 1., assignor to General Motors Corporation,Detroit, Mich a corporation of Delaware ApplientionOctoher 17, 1956,Serial No. 616,522

' 9 Claims. 123-493) The present invention relates to a throttle controlmechanism particularly adapted for use with a carburetor governingsystem. The mechanism is particularly designed for use with a compoundtype carburetor in which it is necessary to control a plurality ofsequentially operating throttles.

It has been found desirable, particularly with commercial vehicles suchas trucks and busses, to provide means whereby the engine is protectedagainst operation at excessive speeds which would otherwise bedestructive thereof. One most satisfactory way to thus govern the speedof an engine is through the carburetion system whereby as excessiveengine speeds are approached a speed responsive mechanism causes thecarburetor to reduce the supply of combustible mixture flowing to theengine. This type of governing system has been satisfactorily utilizedin the case of simple or non-compound type carburetors in which thethrottle controllingv mechanism is required to operate a single throttleor where a plurality of throttles operate in phase, i. e.,non-sequential operation.

In a carburetor of the type using sequentially operating throttles, i;e., where one throttle is adapted to open at a different rate thananother, the actuating mechanism tendsto be somewhat complicated. Theneed for adding a governing function and its attendant mechanism to sucha carburetor has presented an extremely dilficult situation both. from afunctional as well as structural viewpoint.

The present invention has for its primary object the solution ofgoverning a compound type carburetor through the use of a uniquethrottle controlling mechanism which will hereinafter be described indetail.

In the drawings:

Figure 1 is an elevational view of a carburetor embodying the subjectinvention;

Figure 2 is a partially sectioned view along line 22 of Figure 1;

Figure 3 is a view along line 3-3 of Figure 2; and

Figure 4 illustrates the carburetor governing system.

The present invention has been illustrated with a compound typecarburetor of the four-barrel typeas generally shown in copendingapplication Serial No. 264,136, now Patent No. 2,771,282, Olson et al.,filed December 29, 1951. It is, of course, obvious that the invention isnot limited to any particular type or configuration of a compoundcarburetor and may be adapted for use with any carburetor utilizingsequentially operating throttles.

The carburetor per se, will be described only insofar as it is necessaryto provide sufiicient background for the present invention. Thecarburetor is generally indicated at and includes a plurality ofinduction passages 12, 14, 16 and 18 in each of which is respectivelydisposed a throttle 20, 22, 24 and 26 for controlling the flow ofcombustible mixture through the induction passages. Primary-throttles 20and 22 are fixed on a rotatable shaft 28 and move in unison to controlthe primary induction passages 12 and 14. Similarly the secondarythrottles 24 and 26 are fixed upon a rotatable shaft 30 to control thesecondary induction passages 16 and 18.

Shaft 28 extends from the main body of the carburetor into a casing 32formed on the carburetor body and adapted to be closed by a suitablecover 3 4. Fixed by a nut 36 on that portion of shaft 28 within casing32 is a T-shaped lever 38. Similarly fixed on the secondary throttleshaft 36 is a bifurcated lever 40 having spaced arms 42 and 44. A leveris loosely mounted on the secondary throttle shaft 34 proximate fixedvlever 40 and includes a tang or lip 48 which projects between arms 42and 44 of lever an. Alink 56 is articulated at one end to an arm 52 oflever 38 and is similarly articulated at the other end to an arm 54. oflever 46.

Levers 40 and 46 are resiliently coupled together through a helicalspring 56 which is. coiled about shaft 30 intermediate the levers andterminates in end portions respectively fixed to arms 44 and 54 oflevers 4i) and 46. Spring 56 biases lever 49 in a counterclockwise orclosing direction. The space between arms 42 and 44 as well as the loosemounting of lever 46 on shaft 3% provides for relative movement betweenthese levers for a purpose to be subsequently discussed.

Arm 60 of lever 38 includes a stud member 62 projecting therefrom and towhich is connected one end of a coiledspring-member 64-. The other endof spring 64 is fixed to a stud 66 mounted on the carburetor body. Thestud 52 of lever 33 is radially spaced from the primary throttle shaft28 so that the spring 64 continuously exerts a throttle opening momentto the lever and shaft. In general, it will 'be seen that through lever38; link 50 and levers 4t) and 46; the opening movement of the primarythrottle may also have an opening effect on the secondary throttle, thedetails of which will now be discussed.

As shown in Figures 1 and 2 the various links and levers are in aposition in which both the primary and secondaryv throttles are closed.In this position it will be seen that arm 54 of secondary throttlecontrolling lever 46 and link 50 are so relatedto. lever 38 that theinitial opening movement of the primary throttle under the influence ofspring 64 will cause arm 52 of lever 38 to pivot about the associatedend of link 50 and also for the other end of the link to pivot about itsconnection with arm 54 of lever 46 without transmitting any rotarymovement to lever 40. Thus, initially there. is no significanttranslatory movement of link 50- thereby permitting an opening movementto be imparted to the primary throttles 20 and 22 without affecting anyopening of the secondary throttles. Once the arm 52 and the associatedend of link 50 have moved sufficiently overcenter to have exhausted thepivotal movement referred to, continued throttle opening orcounterclockwise movement of the primary throttle lever 38 will begin toimpart a clockwise rotation to lever 4-6. Due to the space between thearms 42 and 44 of bifurcated lever 40 and the intermediate position.therebetween of tang 48:, a further incremental opening movement of theprimary throttle will be permitted until such time as the tang engageswith arm 44 of lever 40. The various members may be suitablyproportioned to permit any desired degree of opening of the primarythrottles before the actuation of the secondary throttles begins. In thedevice, as shown, the mechanism will permit the primary throttle to moveto a position approximately 46 from the horizontal or approximately 50%open before actuation of the secondary throttle commences.

With the tang 48 engaging arm 44, further opening movement of theprimary throttle will impart anopening movement to the secondarythrottle which will continue to open during the remaining openingmovement of the primary throttles but at a faster rate than the,

. ype

primary throttles so that both primary and secondary throttles willreach full open position at substantially the same time.

While the spring means 64 provides the actual opening force for thethrottles it is necessary to provide a manual control therefor in orderthat the operator may actually pre-select and control the degree ofthrottle opening and hence the speed of the engine. To this end, primarythrottle shaft 23 also extends through the carburetor in the oppositedirection from casing 32 and has a lever fixed to the end thereof. Lever70 includes a projection 72 adapted to be engaged by a similarprojection 74 on a lever 76 rotatably mounted in a cover 78 suitablyfixed to the carburetor housing. Levers 7t) and 76 are coaxially relatedin such a way that the opening movement of primary throttle shaft 28 isinhibited by the angular position of the lever 76, the latter which iscontrolled through a suitable linkage mechanism, not shown, to theaccelerator pedal. Thus with the accelerator pedal released indicatingno need for power beyond idling, projection 74 on lever 76 engagesprojection 72 on lever 70 to maintain the throttles in a closed positionagainst opening force of spring 64. As the operator gradually depressesthe throttle, lever 76 will progressively rotate in a clockwisedirection permitting the spring 64 to rotate shaft 28 an equal amount toopen the throttles to the extent determined by the operator. For reasonsto be subsequently discussed, it should be noted that projections 72 and'74 upon levers 70 and 76 are so related that the throttles may beclosed without any regard for the position of lever 76 or theaccelerator pedal.

In order to govern the carburetor and hence prevent the engine fromoperating at speeds which will be detrimental thereto, a governingmechanism is provided which includes a servomoto-r 8t} fixed to orintegral with throttle linkage casing 32. The servomotor 80 includes apair of casing members 82 and @4- having a flexible diaphragm 86peripherally clamped therebetween in order to divide the casing into apair of chambers 88 and 90. Suitably fixed to the diaphragm 86 is anactuating rod or link 92, the other end of which is articulated to arm94 of primary throttle control lever 38. The con- 'nection between link92 and lever 38 is diametrically opposite the connection between theaforesaid lever and spring 64. In this way the spring and diaphragm areadapted to provide opposite actuating forces on the primary throttleshaft 28 as will now be considered.

Servo chamber 88 is communicated through a pas- I sage 96 and a conduit98 to the carburetor induction passage posteriorly of the throttles soas to convey manifold vacuum to said chamber which may act to move thediaphragm to the right, as shown in Figure 1, and close the throttles.Conduit 98 registers with a passage 100 formed in throttle body 101 andwhich latter passage terminates, as noted, in the induction passage 12posteriorly of throttle 20. Orifices 102 and 104 are re spectivelyprovided to determine generally the rate of servo actuation.

The influence of manifold vacuum on said diaphragm is, however, underthe influence of a speed responsive mechanism indicated generally at andwhich mechanism permits atmospheric air to be bled into chamber 88 todestroy the vacuum therein until such time as the speed of the enginereaches a value sufiiciently high to shut off the atmospheric bleed.

The speed responsive mechanism 110 may be of the shown and described inPatent 2,664,867, Hartzell et al., filed February 14, 1951, and doesnot, per se, constitute a part of the present invention. The speedresponsive mechanism is pertinent to the subject invention only incombination with the subject unique throttle controlling linkagearrangement. Insofar as the present invention is concerned it willsufiice to say of the speed responsive device 110 that it includes ashaft 112 driven at engine speed through a gear 114 connected in turnwith a member 116 on the engine cam shaft. Radially mounted on the shaft112 is a centrifugal valve mechanism 120 which is biased by spring 122in a position in which spindle 124 uncovers port 126 admittingatmospheric air from an air cleaner conduit 128 to a passage 130 formedin shaft 112. Passage 130 in turn communicates at its other end with anannular chamber 132 in registry with a passage 134 connecting withconduit 136 communicating with the servo casing 82. Thus, as long asengine speed remains below a value which will permit safe operation ofthe engine, valve 120 continues to bleed atmospheric air to the servochamber 88 precluding manifold vacuum from having any effect on thethrottle actuating mechanism. When the engine exceeds a given value, themagnitude of which may be controlled by adjusting the rate of spring 122through a nut 138 threaded on the valve spindle, centrifugal weight 140closes port 126 shutting off the atmospheric bleed and enabling manifoldvacuum to move diaphragm 86 to the right and thereby move primarythrottle lever 38 in a clockwise or closing direction.

In so moving the primary throttle lever 38, link 50 and lever 46 aremoved until tang 48 engages arms 42 of lever 40 imparting acounterclockwise or closing movement to the secondary throttles 24 and26. Thus no matter how far the accelerator pedal is depressed thegoverning mechanism will insure that the maximum safe speed at which theengine can be run .will not be ex ceeded. It is to be recalled at thisjuncture that projections 72 and 74 on levers 70 and 76 coact to providewhat is in effect a one-Way clutch between the accelerator pedal ormanual control and the throttles whereby the accelerator determines theextent to which the throttles may be opened but the closing of whichthrottles may be over-controlled by the governing mechanism asdescribed.

It is to be understood that structural modifications may be made in thethrottle controlling mechanism described without departing from thescope of the invention.

I claim:

1. A compound carburetor comprising primary and secondary inductionpassages, throttles for respectively controlling flow through saidpassages, each throttle being fixed upon a rotatable shaft, first andsecond levers respectively fixed to the primary and secondary throttleshafts, a third lever rotatably supported upon the secondary throttleshaft, 2. link articulated between said first and third levers, meanscontinuously urging said primary throttle toward open position, a lostmotion connection between said second and third levers permitting afixed amount of opening movement of said primary throttle before thesecondary throttle begins to open, manually controlled means opposingthe opening movement of the primary throttle, and a control deviceresponsive to an engine operating condition for moving said first leverto .close said throttles against the opening force of said resilientmeans.

2. A compound carburetor comprising primary and secondary inductionpassages, throttles respectively controlling fiow through said passages,each throttle being fixed upon a rotatable shaft, first and secondlevers respectively fixed to the primary and secondary throttle shafts,a third lever rotatably supported upon the secondary throttle shaft, alink articulated between said first and second levers, meanscontinuously urging said primary throttle toward open position, saidsecond lever being bifurcated to provide a pair of spaced arms, saidthird lever including a tang portion extending between said arms andadapted to move relatively thereto, a resilient member connecting saidsecond and third levers, said link, second and third levers beingconstructed to permit initial opening of said primary throttle beforethe secondary throttle begins to open, manually controlled meansopposing the opening movement of the primary throttle, and a controldevice responsive to an engine operating condition for moving said firstlever to close said throttles against the opening force of saidresilient means.

3. A compound carburetor comprising primary and secondary inductionpassages, throttles for respectively controlling flow through saidpassages, each throttle being fixed upon a rotatable shaft, first andsecond levers respectively fixed to the primary and secondary throttleshafts, a third lever rotatably supported upon the secondary throttleshaft, a link articulated between said first and third levers, meansconnected to said first lever for continuously urging said primarythrottle toward open position, a lost motion connection between saidsecond and third levers permitting a fixed amount of opening movement ofsaid primary throttle before the secondary throttle begins to open,manually controlled means opposing the opening movement of the primarythrottle, and a control device articulated to said first lever andresponsive to an engine operating condition for moving said first leverto close said throttles against the opening force of said resilientmeans.

4. A compound carburetor comprising primary and secondary inductionpassages, throttles for respectively controlling flow through saidpassages, each throttle being fixed upon a rotatable shaft, first andsecond levers respectively fixed to the primary and secondary throttleshafts, a third lever rotatably supported upon the secondary throttleshaft, a link articulated between said first and third levers, meansconnected to said first lever for continuously urging said primarythrottle toward open position, a lost motion connection between saidsecond and third levers permitting a fixed amount of opening movement ofsaid primary throttle before the secondary throttle begins to open,manually controlled means opposing the opening movement of the primarythrottle, and a control device articulated to said first lever on theopposite side of the primary shaft axis and responsive to an engineoperating condition for moving said first lever to close said throttlesagainst the opening force of said throttle opening means, said linkbeing articulated to the first lever intermediate the connections ofsaid primary throttle opening means and the control device.

5. A compound carburetor comprising primary and secondary inductionpassages, throttles for respectively controlling flow through saidpassages, each throttle being fixed upon a rotatable shaft, first andsecond levers respectively fixed to the primary and secondary throttleshafts, a third lever rotatably supported upon the secondary throttleshaft, a link articulated between said first and third levers, meanscontinuously urging said primary throttle toward open position, a lostmotion connection between said second and third levers permitting afixed amount of opening movement of said primary throttle before thesecondary throttle begins to open, a manually controlled lever rotatablymounted on said carburetor proximate said primary throttle shaft, saidmanually controlled lever being rotatable relative to the primarythrottle shaft and adapted to engage the latter to limit the openingmovement thereof, and a control device responsive to an engine operatingcondition for moving said first lever to close said throttles againstthe opening force of said resilient means.

6. A compound carburetor as defined in claim 5 in which said manuallycontrolled lever is coaxially aligned with said primary throttle shaftand disposed on the opposite side of said carburetor from said firstlever.

7. A compound carburetor comprising primary and secondary inductionpassages, throttles for respectively controlling flow through saidpassages, each throttle being fixed upon a rotatable shaft, first andsecond levers respectively fixed to the primary and secondary throttleshafts, a third lever rotatably supported upon the secondary throttleshaft, a link articulated between said first and third levers, meanscontinuously urging said primary throttle toward open position, a lostmotion connection between said second and third levers permitting afixed amount of opening movement of said primary throttle before thesecondary throttle begins to open, a fourth lever fixed to said primarythrottle shaft and having a projection extending therefrom, a manuallycontrolled lever rotatably mounted on said carburetor proximate saidprimary throttle shaft and having a projection disposed proximate thefourth lever projection, said manually controlled lever being rotatablerelative to the primary throttle shaft whereby the manual leverprojection is engaged by the fourth lever projection to limit theopening movement of said latter lever, and a control device responsiveto an engine operating condition for moving said first lever to closesaid throttles against the opening force of said resilient means.

8. A compound carburetor comprising primary and secondary inductionpassages, throttles respectively controlling flow through said passages,each throttle being fixed upon a rotatable shaft, first and secondlevers respectively fixed to the primary and secondary throttle shafts,a third lever rotatably supported upon the secondary throttle shaft, alink articulated between said first and second levers, meanscontinuously urging said primary throttle toward open position, saidsecond lever being bifurcated to provide a pair of spaced arms, saidthird lever including a tang portion extending between said arms andadapted to move relatively thereto, a resilient member connecting saidsecond and third levers, said link, second and third levers beingconstructed to permit initial opening of said primary throttle beforethe secondary throttle begins to open, manually controlled meansopposing the opening movement of the primary throttle, a servomotorhaving a pressure responsive member, means connecting said member andsaid one throttle, a passage communicating manifold vacuum to saidpressure responsive member to actuate said member and move saidthrottles toward closed position, a valve normally bleeding said passageto atmosphere, and engine speed responsive means adapted to close saidatmospheric bleed.

9. A compound carburetor comprising primary and secondary inductionpassages, throttles for respectively controlling flow through saidpassages, each throttle being fixed upon a rotatable shaft, first andsecond levers respectively fixed to the primary and secondary throttleshafts, a third lever rotatably supported upon the secondary throttleshaft, a link articulated between said first and third levers, meansconnected to said first lever for continuously urging said primarythrottle toward open position, a lost motion connection between saidsecond and third levers permitting a fixed amount of opening movement ofsaid primary throttle before the secondary throttle begins to open,manually controlled means opposing the opening movement of the primarythrottle, a servomotor having a pressure responsive member articulatedto said first lever on the opposite side of said primary shaft axisrelative to said throttle opening means, a passage communicatingmanifold vacuum to said pressure responsive member to actuate saidmember and move said throttles toward closed position against the firstof said throttle opening means, a valve normally bleeding said passageto atmosphere, and engine speed responsive means adapted to close saidatmospheric bleed, said link being articulated to the first leverintermediate the connections of said primary throttle opening means andthe pressure responsive member.

References Cited in the file of this patent UNITED STATES PATENTS2,393,556 Olson et al. Jan. 22, 1946 2,399,080 Udale Apr. 23, 19462,415,510 Mallory Feb. 11, 1947 2,749,100 Carlson June 5, 1956 2,771,282Olson et al. Nov. 20, 1956

